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Purchasing seafood : answering questions of mercury in North Carolina-caught species

Purchasing Seafood
Answering Questions of Mercury in North Carolina-Caught Species
Results from N.C. Fishery Resource Grant Projects
For seafood consumers, deciding which of the many products available to purchase can be confusing. Providing selection criteria is difficult because seafood consumption guidelines can vary based on the individual. Adding to the confusion, recommendations are available from the U.S. Food and Drug Administration (FDA), the U.S. Environmental Protection Agency (EPA), and nongovernmental groups. The FDA and EPA provide information on contaminants in seafood, most notably mercury content. Nongovernmental organizations, which often provide recommendations in the form of seafood cards or digital applications, also include factors associated with the status of the fish stock and how the fish is harvested.
Mercury and Methylmercury
Mercury is a heavy metal that occurs naturally in the environment but is released into the air through natural causes and industrial pollution. It can enter various water bodies where it is converted by bacteria to methylmercury, a form that is toxic to humans, and readily available to aquatic organisms. Methylmercury can accumulate in fish tissues that are eventually consumed by humans.
In fact, the primary source of human exposure to mercury is through seafood (Grandjean et al., 1995). That is why mercury is a major consideration in seafood consumption recommendations. In particular, the nervous systems of fetuses and young children are very sensitive to mercury exposure. As a result, mercury consumption recommendations vary with the intended audience.
Federal Guidelines
EPA provides recommendations on seafood consumption based on methylmercury content. The action level established by EPA is 0.3 parts per million (also reported as 0.3 milligrams per kilogram), a level by which species are considered to have high methylmercury. However, the actual consumption recommendations vary based on the individual and the average number of seafood meals consumed per week. A seafood meal is defined as 6 ounces of a given species.
EPA considers two groups of consumers in their recommendations. The general public are males 15 years and older, and women older than 44 years. Higher-risk individuals are women of childbearing age and children less than 15 years of age. Table 1 shows the maximum number of meals for each group at various methylmercury levels. While figures are provided for those in the higher risk group, it is generally recommended that pregnant or nursing mothers, and young children limit or avoid consuming fish with mercury levels greater than 0.3 ppm.
BluEprints
NORTH CAROLINA SEA GRANT NC Statetatetate Uni versit y BOX 8605 RALEIGH, NC 27695-8605
UNC-SG-BP-12-02
Insufficient Data and New Research
The data on methylmercury content in seafood that is used for consumption advisories in North Carolina is obtained from both in- and out-of-state sources, and often does not accurately reflect what is caught locally. In addition, dated samples further complicate establishing effective guidelines.
In 2010, the N.C. Fishery Resource Grant Program, administered by North Carolina Sea Grant, funded two separate methylmercury studies. Derek Aday, Sally Petre and Dana Sackett from North Carolina State University, and fisherman Dale Britt conducted project 10-ST-02. Duke University researchers Dan Rittschof, Amy Freitag and Nari Sohn, and
Table 1. Maximum seafood consumption limits for consumer group and methylmercury level, based on data from U.S. EPA document EPA 828-B-00-008.
Group
Methylmercury level (ppm)
Maximum number of meals per week
Maximum amount of seafood per week (oz)
Higher risk 1
0.1
0.2
0.3
0.5
1.0
2.0
3.0
1.5
1.0
0.5
0.3
0.2
18
9
6
3
2
1
General public 2
0.1
0.2
0.3
0.5
1.0
2.0
9.4
4.7
3.1
1.9
0.9
0.5
56
28
19
11
5
3
1. Women of childbearing age and children less than 15 years of age.
2. Males 15 years and older, and women older than 44 years.

Purchasing Seafood
Answering Questions of Mercury in North Carolina-Caught Species
Results from N.C. Fishery Resource Grant Projects
For seafood consumers, deciding which of the many products available to purchase can be confusing. Providing selection criteria is difficult because seafood consumption guidelines can vary based on the individual. Adding to the confusion, recommendations are available from the U.S. Food and Drug Administration (FDA), the U.S. Environmental Protection Agency (EPA), and nongovernmental groups. The FDA and EPA provide information on contaminants in seafood, most notably mercury content. Nongovernmental organizations, which often provide recommendations in the form of seafood cards or digital applications, also include factors associated with the status of the fish stock and how the fish is harvested.
Mercury and Methylmercury
Mercury is a heavy metal that occurs naturally in the environment but is released into the air through natural causes and industrial pollution. It can enter various water bodies where it is converted by bacteria to methylmercury, a form that is toxic to humans, and readily available to aquatic organisms. Methylmercury can accumulate in fish tissues that are eventually consumed by humans.
In fact, the primary source of human exposure to mercury is through seafood (Grandjean et al., 1995). That is why mercury is a major consideration in seafood consumption recommendations. In particular, the nervous systems of fetuses and young children are very sensitive to mercury exposure. As a result, mercury consumption recommendations vary with the intended audience.
Federal Guidelines
EPA provides recommendations on seafood consumption based on methylmercury content. The action level established by EPA is 0.3 parts per million (also reported as 0.3 milligrams per kilogram), a level by which species are considered to have high methylmercury. However, the actual consumption recommendations vary based on the individual and the average number of seafood meals consumed per week. A seafood meal is defined as 6 ounces of a given species.
EPA considers two groups of consumers in their recommendations. The general public are males 15 years and older, and women older than 44 years. Higher-risk individuals are women of childbearing age and children less than 15 years of age. Table 1 shows the maximum number of meals for each group at various methylmercury levels. While figures are provided for those in the higher risk group, it is generally recommended that pregnant or nursing mothers, and young children limit or avoid consuming fish with mercury levels greater than 0.3 ppm.
BluEprints
NORTH CAROLINA SEA GRANT NC Statetatetate Uni versit y BOX 8605 RALEIGH, NC 27695-8605
UNC-SG-BP-12-02
Insufficient Data and New Research
The data on methylmercury content in seafood that is used for consumption advisories in North Carolina is obtained from both in- and out-of-state sources, and often does not accurately reflect what is caught locally. In addition, dated samples further complicate establishing effective guidelines.
In 2010, the N.C. Fishery Resource Grant Program, administered by North Carolina Sea Grant, funded two separate methylmercury studies. Derek Aday, Sally Petre and Dana Sackett from North Carolina State University, and fisherman Dale Britt conducted project 10-ST-02. Duke University researchers Dan Rittschof, Amy Freitag and Nari Sohn, and
Table 1. Maximum seafood consumption limits for consumer group and methylmercury level, based on data from U.S. EPA document EPA 828-B-00-008.
Group
Methylmercury level (ppm)
Maximum number of meals per week
Maximum amount of seafood per week (oz)
Higher risk 1
0.1
0.2
0.3
0.5
1.0
2.0
3.0
1.5
1.0
0.5
0.3
0.2
18
9
6
3
2
1
General public 2
0.1
0.2
0.3
0.5
1.0
2.0
9.4
4.7
3.1
1.9
0.9
0.5
56
28
19
11
5
3
1. Women of childbearing age and children less than 15 years of age.
2. Males 15 years and older, and women older than 44 years.